In the past, various efforts were made to provide a system for preparing a hemodialysis solution from dry chemicals and water on a large scale batch basis. Some systems transferred the packaged dry chemicals into a mixing vessel by creating a water slurry from the dry chemicals and aspirating the slurry into a mixing tank where it was dissolved with additional water to form a solution with a desired concentration of chemicals therein. Other systems depended on the user manually adding the dry chemicals to the mixing tank. The ability to rapidly transfer and dissolve the dry chemicals has continued to be an obstacle in both types of systems in that the dry chemicals settle to the bottom of the mixing tank, resulting in prolonged dissolution periods with conventional agitation of the contents of the mixing tank. The present invention provides an improved transfer mechanism to deliver the dry chemicals to a mixing tank, and further provides a mixing tank and recirculation apparatus that create high turbulence at the bottom of the tank that accelerates formation of the desired solution and promotes uniformity in the chemical concentration of the solution. Examples of the chemicals to be mixed in the mixing tank of the present invention are the Renasol(copyright) and Centrisol(copyright) acid concentrates or solutions of bicarbonate for hemodialysis concentrates available from the assignee of the present invention. Existing designs for large tanks that mix solutions suffer from several ergonomic shortcomings. These include the inability to fit through a standard door, excessive tank height that makes it difficult to lift powder bags for pouring, and inadequate mixing of these very large volumes, including the creation of xe2x80x9cdead spotsxe2x80x9d where there is not adequate circulation.
The present invention includes a mixing tank for solutions. It has a capacity of up to 110 gallons or more and also has mounting locations for a control panel built into the design that imparts a mixing feature to the tank. The unique shape of the tank includes a forward projecting area with a downward sloping floor which bestows enhanced circulation of the solution. The design increases the volume of the mixer while maintaining a waist height profile. In addition, the narrow width also allows it to fit through a standard door. The location for the addition of solids to be mixed into solution is ergonomically designed to be close to the front of the tank, and there is a shelf on the top of the tank, so that bags of solids can rest on it while being poured into the tank.